mesa/st/tests: unify MockCodeLine* classes

mesa/st/tests: unify MockCodeLine* classes

 * Merge the classes MockCodeLine and MockCodelineWithSwizzle into
   one, and  refactor tests accordingly.
 * Change memory allocations to use ralloc* interface.

 v2:
 * move the test classes into a conveniance library
 * rename the Mock* classes to Fake* since they are not really
   Mocks
 * Base assertion of correct number of src and dst registers in tests
   on what the operatand actually expects
 * Fix number of destinations in one test

 v6:
 * fix local includes using "..." insteadof <...>

Reviewed-by: Brian Paul <brianp@vmware.com>
Signed-off-by: Gert Wollny <gw.fossdev@gmail.com>